Re: \score

I finally read that section as well as the section on multiple
movements. From the examples I *might* infer that only piece and
opus can be changed in a new score.

That is correct. If it isn't clear, I'll look at making it more
clear. (or ideally, you could tell me how to make it more clear. :)

However, the manual for version 2.7 also tells how to include
all headers for every movement, by setting the printallheaders
variable.

I have not seen that yet. Ok. I see the manual I am now looking at is
for 2.7.28 and what you say is there. I now have no access to the
2.7.27 manual to see if that's why I missed it.

I see that printallheaders = ##t does what it says and prints all the
headers - even again for the first movement. I only want some centered
movement title like much common printed music not all the titles, etc.
I'm not sure if your solution will do what I am describing.

I would think an ideal solution would be a "movement" header element
which did what I am describing working like piece and opus and being
centered. Would you agree that movement name is more commonly centered
that instrument name even though I have seen examples of instrument name
in the center?

Is there a way to have a movement title centered above the new
movement which is the way most orchestral parts I read are done?

The easiest way is to simply stick them in separate ly files.

Can separate ly files be put on the same page without using LilyPond
Book?

The most interesting way is to redefine scoreTitleMarkup. (I think
that's the right name -- take a look at the bottom of "Creating
titles".)

It's not clear how that will solve the problem of centered movement
names over individual movements *on the same page* (which I hadn't
made clear before).

With printallheaders=##t, you can use the ordinary title or
subtitle fields, otherwise you can redefine how the titles for
each subsequent score is printed, for example by
\paper {
bookTitleMarkup = \markup {
\fill-line {
\fromproperty #'header:piece
}
}
}
which should center the "piece" field if I'm not mistaken.

It may take me a little while to test that and I'm not sure how to use
it yet. Will that allow me to have different movement names since
\paper applies to the whole ly file?